Yeniçağa is a town and a district of Bolu Province in the Black Sea region of Turkey, 38 km from the town of Bolu, on the highway from Istanbul to Ankara. It covers an area of 225 km², and the population (2000) is 10,800 of which 5,953 live in the town of Yeniçağa. Elevation is about 1200 m. The mayor is Recai Çağlar (AKP).
The district is on the inland side of Bolu Mountain and has a cold, hard, dry inland climate; the countryside is pine-forested on the northern and western parts of the district whereas the south-eastern parts are sparsely wooded hills.
Yeniçağa is a small town providing basic infrastructure to the surrounding countryside, and successive generations have migrated to large cities in Turkey or abroad in search of jobs and careers. There are a large number of roadside restaurants, gas stations and repair shops along the old E5 Istanbul highway, these are mainly used by trucks as cars zoom by on the newer TEM motorway. Yeniçağa Lake is a popular spot for picnics under the trees on the lakeshore. There is an annual country fair (panayır).